We have recently shown that the synthesis of the enzyme ribonucleotide reductase, the first enzyme unique to the pathway leading to DNA, is controlled in the same way as initiation of DNA replication. We plan to see if this enzyme is synthesized continuously or cyclicly. We will determine whether other procaryotic as well as some eucaryotic organisms control the synthesis of this enzyme in a similar manner. We plan to use DNA-RNA hybridization assays to quantitate the synthesis of the messenger RNA coding for this enzyme to further our investigation. Another area that we plan to investigate is the enzyme system that couples NADPH oxidation to reduction or ribonuceotide by utilizing genetic as well as biochemical techniques. We also plan to investigate how the radical that is part of this enzyme is generated and stabilized in vivo.